1. Field of the Invention
The present invention pertains to a modular check valve particularly adapted for high pressure fluid service and characterized by a swinging disc closure member mounted within a generally cylindrical tubular body having interchangeable end or head members.
2. Background Art
In the art of fluid handling devices a number of inventions have been developed pertaining to so called one way or check valves for preventing reverse flow of fluids in a conduit. One type of valve which has been found suitable for fairly large diameter conduits and relatively high flow rates is known as a so called swing type check valve comprising a generally disc shaped closure member which is pivotally mounted on an arm for movement between an open through flow position and a closed position wherein the disc is seated against a valve seat arranged generally perpendicular to the direction of flow. A number of different swing type check valves have been developed for various types of service. However, there is an increasing demand for valves which are capable of operating in systems wherein fluid pressures may range as high as several thousand pounds per square inch. When the service requirements include the capability of operating at relatively high pressures particular problems must be dealt with in the design of swing type check valves and the like. These problems are further aggravated for valves used in certain specialized applications such as, for example, the pumping of highly abrasive and/or corrosive fluids such as are used in certain stimulation and recovery procedures for subterranean hydrocarbon deposits.
It has been determined that in the development of swing type check valves for high pressure applications and severe service conditions such as are encountered in fluid systems for stimulating recovery of underground petroleum deposits that it has been desirable and necessary to abandon known design concepts for both the valve body and seat components. For example, it has been determined that conventional cast or forged valve bodies having removable access covers or other structural features which create an unsymmetrical shape are disadvantageous in that stress raisers are formed which cannot be tolerated under the aforementioned severe operating conditions. It is particularly difficult to obtain cast bodies which are free of defects or material porosity so as to be suitable for high pressure operation. Moreover, for valves used with volatile or corrosive fluids it is also necessary to minimize the number of potential leakage points in the valve body which are formed by removable covers, inspection ports or valve pivot pin bores, for example.
Accordingly, the needs associated with high pressure applications of swing type check valves, and in particular, applications involving abrasive and/or corrosive fluids have presented new problems which have heretofore been unresolved. Not only have extreme service requirements presented new problems but the need to provide interchangeability of parts for field replacement or repair, and the need to provide a modular design which may be easily adapted to different types of conduit coupling arrangements have further complicated the requirements for swing type check valves which are economical to produce and yet capable of performing under rigorous service conditions.